SSC JE Civil Engineering 2017 Set 1 Solved Paper

Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200°C) and pressure (150 mega pascals) causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock.